Turbine



- -OC- 14, 1947- .g y R.' BQ SMITH :TAL 2,428,999

.Tunamn Filedxgron' `l1, 1945 2 sneet-snt 1 wlQEssEszv l .VENT Rs MW" y WQ ATTORNEYS Patented Oct. 14, 1947' TURBIN E Ronald B. Smithfand Fritz 0. vHenng," Greens burg, Pa., assignors to Elliott Company, Jeannette, Pa., a corporation of. Pennsylvania Application March 7, 1945, Serial No. 581,508 11 claims. (ci.A 25a- 39) This invention relates to gas turbines, and more particularly to the rotor cases and surrounding housings of axial flow turbines.

In gas turbines of the axial rflow type the rotor is enclosed by a case which, for assembly purposes, is divided in an axial plane into two half sections that are detachably fastened together in most instances by boltsv extending through longitudinal flanges with which the case is provided at its joints. These flanges increase the wall thickness of the case at the joints, so that 'while the temperature of the case is changing,

during changes in load on the turbine, the case does not expand in a uniform manner but is dis-y torted. This places undesirable stresses on the equally. It also is not uncommon to enclose the rotor case in a housing to form an intermediate chamber that opens into the turbine. exhaust.

.Such housings likewise are provided with flangedv longitudinal joints so that a housing can be opened and removed radially from the rotor case to expose the case and the elements inside of it for inspection or repair. Thermal distortion problems are not of such serious consequence in ,the case of the housing itself, but the housings longitudinal joints intersect annularjoints wherev the ends of the housing are fastened in position, and thereby form three-cornered joints which areA very diiicult to make iluid tight.

It is among the objects of this invention to provide a gas turbine for very high temperatures in which the main supporting structure is thermally elastic and is symmetrical and circular in cross section with fiangeless longitudinal joints; in which said main structure is provided with end bells that are made in one piece; in which there is an outside housing that catches gas leakage and is ilexible and free fromlongitudinal joints; and in which the housing can readily be moved to expose the inside of the turbine without moving the ducts connected thereto.

In accordance with this invention the high temperature structure of our turbine consists essentially of a longitudinally split center section or rotor case having a unitary end bell atv each end forming its end walls and the inlet and outlet of the turbine. Although the rotor case is provided with the usual longitudinal joints, it is free of the customary joint flanges with which the two sections of such a case generally have been provided heretofore. Instead, the case is made symmetrica] in cross section, and its two sections are secured together by bolts disposedin openings in the case wall at both sides of each joint Ycase and also affects the clearances therein unf 2 and perpendicular to the plane of the joints. Preferably, the bodyof the vcase is encircled by a plurality of axially spaced ribs that are integral with the body, and the bolt openings are formed in the portions of these ribs adjacent the joints.A

In order to catch the leakage from the high temperature structure, the rotor case is surrounded by a flexible housing that is spaced from itk and that is free of cross joints. .One end of the housing is detachably connected to the inlet end. of the case, while the opposite end of the housing is closed by` an exhaust casing that has spaced end walls .the inner one of which surrounds theY adjacent end of the housing so that the housing and the outlet oi the rotor case both open-,intothe exhaust casing. The .housing is detachably connected to the surroundingcasingv wall, and, when disconnected from the rotor case and exhaust casing, can be moved axially into the exhaust casing to expose the ,rotor case.

Preferably, the housing is formed of telescoping annular sections which are detachably connected together in extended position by bolts orl the like inserted in overlapping radial anges with which adjacent ends of the sections are'provided. No running parts are connected to the housing, which is made of very thin material, so it can be distorted by expansion of the ductwork connected to the exhaust casing without affecting the operation of the turbine.

Theinvention is illustrated in the accompanying drawings in which Fig. 1 is a side view of our turbine with Vthe outside housing and the end casings partly broken away; Fig. 2 is an enlarged' fragmentary section of the rotor case taken on the line II-II-of Fig. 1; Fig. 3 is a fragmentary horizontal view taken on the line III-III of Fig. 2; Fig. 4 is a reduced view of the outer end of the inlet casing; Fig. 5 is a fragmentary view of the left-hand end of the ,inlet end bell; Fig. 6 is a fragmentary vertical sectiontaken on the line `VIVI of Fig. 5; Fig. 7 is a fragmentary view of the right-hand end of the inlet end bell; and Figs; 8, 9, and 10 are views corresponding to Figs. 5, 6, and 7, respectively, of the outlet end bell.

Referring to Fig. 1 of the drawings, a bearing housing l at one end of a gas turbine is supported by a pair of upright links 2 pivotally mounted onl a suitable foundations.Y A similar bearing housing 4 at the opposite end of the turbine is supported in iixed position on a support 5,

so links 2 allow for thermal expansion and contraction of the entire turbine axially. Journaled inside the bearing housings are rotor shafts 6 (indicated inv dotted lines) the inner ends of which 3 support a turbine rotor (not shown). The outer end of the rotor shaft in bearing I carries a coupling 1 for connecting it to the shaft that is to be driven by the turbine.

The inner end of bearing housing I supports an end bell 8, preferably formed in one piece, that forms one end of the turbine cylinder. This cylinder, or main supporting structure, includes a case 9 encircling the rotor and supporting the usual bladed diaphragms (not shown) disposed in the customary manner between the rows of rotor blades. The end bell, which has a central opening for the adjacent rotor shaft S, has a, wall IIJ that iiares outwardly away from that Vopening and 4the adjacent end of the case to provide a circular inlet for admission of hot gases to the end of the case. For-supporting the inlet end of the case from end wall I0, a plurality of uniformly spaced radiating tie members l I are formed integral with the inner surface of the wall. The outer end portions of these members leave the wall and extend across the space between it and a flange I2 encircling the end of the case with which the flange is integral. The outer ends of the tie members are joined to a ring I3 to which case ange I2 is secured by bolts I4, and the ring i projects radially outwardly from the flange.

An inlet casing I6, for delivering hot gases to the turbine, surrounds the turbine inlet and has spaced annular end walls I1 and I8 welded to the outer edges of end wall I and ring I3 which form the opposite sides of the circular inlet. This casing is provided with an inlet I9 adapted to be connected to the duct work of the plant.

The inner end of the other bearing housing 4 l extends into and supports an end bell 2|, also preferably made in one piece, at the outlet end of the rotor case. This bell includes a conical wall 22 that diverges away from the case and is provided with a plurality of uniformly spaced radiating tie members 23. The outer end portions of `these members extend toward the case across its circular outlet and are joined to a ring 24 that is bolted to a flange 25 encircling the outlet end of the case.

The outlet of the 'case opens into an exhaust casing 3|] that has spaced annular end walls 3| and 32, the outer one of'which is bolted to the flanged outer edge of the adjacent end wall 22.` The inner end wall 3| of the casing is provided with a large central opening 33 to space it a considerable distance from the adjacent end bell 2| which it encircles. This casing is provided with an outlet 34 adapted to be connected to an exhaust duct.

The rotor case 9, which is circular in cross section, is divided in an axial plane into two half sections so that they can be tted around the rotor when the turbine is assembled.v In order to make the case symmetrical in cross section, the cases horizontal joints are not provided with the usual flanges for bolting the two sections together. Instead, the wall thickness of the case in any giVen transverse plane is substantially uniform, and the body of the case is encircled by a plurality of axially spaced ribs 36 that are integral with it to increase the wall thickness uniformly around the case at several points.

Near the joints these ribs are bored and counterbored to provide them with vertical openings 31 that extend more or less lengthwise of the ribs and are perpendicular to the plane of the joints, as shown in Fig. 2. Bolts 3B, threaded at both ends, are inserted in these vertical openings for connecting the two sections of the case together 4 when long nuts 39 are screwed onto the bolts. The central portion of each bolt is enlarged to fit snugly in openings 31 and thereby serve as a dowel. As the bolt-receiving openings are formed in ribs 36, the wall of the case is not weakened by them. With this form of case, thermal expansion and contraction take place nearly uniformly while the temperature of the case is changing and without the usual distortion stresses. and the clearances within the case thereby are maintained. The end bells 8 and 2| for the case, being symmetrical and free of joints, likewise expand and contract uniformly.

Leakage of gas out of the rotor case through its horizontal joints is more or less expected, but this leakage is caught by a housing 4I encircling the case in the space between the inlet and exhaust casings. This housing is spaced from the case to form a chamber 42 that opens into the exhaust casing around end bell 2|. The housing is formed from a pair of jointless rings or shells 43 and .44 that normally are detachably connected end to end. One shell is smaller than the other so that they can be telescoped when they are disconnected. The shells can have very thin walls because they have no horizontal joints and because the housing is not subjected to high pressure from within. Sheet metal is suitable for the shells. The smaller shell 43 is encircled at its opposite ends by radial flanges 46 and 41, the first of which is bolted tightly to ring I3 of end bell 8. The other shell 44 encircles the other flange 41 of the first shell and is provided with an inwardly projecting radial flange 48 that overlaps flange 41. These two flanges are detachably connected together by bolts 49. The outer end of outer shell -44 is encircled by a radial flange 5| disposed in the plane of opening 33 in the inner end wall of exhaust casing 30, casing wall 3| are connected together by a separate ring 52 that encircles shell 44 and is provided with two sets oi openings, one set registering with openings in the casing wall, and the other set registering with openings in housing ange 5I. Bolts 53 in these openings fasten the three members together. The radial joints by which the housing shells are connected together and to end bell 8 and casing 30 are easy to seal by any suitable annular sealing members. important feature is that even though expansion of the exhaust duct exerts pressure on housing 4I, the thin walls of the housing allow it to zx and distort without harm. As no running parts areconnected to the housing, its distortion does not affect the operation of the turbine.

When, for any reason, it is desired to gain access to the rotor case, housing 4I is disconnected from ring I3, and the inner ring of bolts 53 are removed to free housing flange 5I from bolting ring 52. When the two sections of the housing have been disconnected from each other by removing bolts 49, the housing shells can be telescoped and moved axially into exhaust casing 30 far enough to expose the rotor case.

According to the provisions of the patent statutes, we have explained the principle and construction of our invention and have illustrated and described what we now consider to represent its best embodiment. However, we desire to have it understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specically illustrated and described.

We claim:

l. A gas tu;bine comprising a rotor case of This ilange and A Veryv circular and symmetricalcross section open at lts opposite ends, said case being divided in an axial plane into two half sections having flangeless joints extending lengthwise thereof, means detachably' fastening the case sections together, the wall of the case in any transverse plane having substantially uniform thickness throughout its circumference to provide for uniform expansion and contraction, an annular one-piece end bell disposed at each end of said case, and means detachably connecting the end bells 4to the ends of the case, said end bells having end walls spaced from the case to' form an annular inlet and an annular outlet betweenA the ends of the case and said end walls.

2. A gas turbine comprising a rotor case of circular and symmetrical cross section open at its opposite ends, said case being divided in an axial plane into two half sections having angeless joints extending lengthwise thereof, means detachably fastening the case sections together, the wall of the case in any transverse plane having substantially uniform thickness throughout its circumference to provide for uniform expansion and contraction, an annular one-piece end bell disposed at each end of the said case, each end bell having an end wall and a coaxial ring spaced therefrom by circumferentially spaced tie members joined to both, and means detachably ccnnectng said rings to the ends of the case, whereby annular inlet and outlet openings are formed between said rings and end walls.

3. A gas turbine comprising a rotor case open at its opposite ends, said case having a body circular and symmetrical in cross section encircled by a plurality of axially spaced ribs integral therewith, said case being divided in an axial plane into two half sections having flangeless joints extending lengthwise thereof, means detachably fastening said case sections together, the wall of the case in any transverse plane having substantially uniform thickness throughout its circumference to provide for .uniform expansion and contraction, an annular one-piece end bell disposed at each end of said case, and means detachably connecting the end bells to the ends of the case, said end bells having end walls spaced from Y the case to form an annular inlet and an annular outlet between the ends of the case and said end walls.

4. A gas turbine comprising a turbine cylinder having an intermediate rotor case vof circular and symmetrical cross section open at its oppositev ends, said case being divided in an axial plane into two half sections having flangeless joints extending lengthwise thereof, means detachably fastening the case sections together, the wall of the case in any transverse plane lhaving substantially uniform thickness throughout its circumference to provide for uniform expansion and contraction, an annular one-piece end bell disposed at each end of said case, means detachably connecting the end bells to the ends of the case, said end bells having end walls spaced from the case to form an annular inlet and an annular outlet between the ends of the caserand said end walls, a fiexible housing having open ends and encircling the case and spaced therefrom, and means connecting one end of the housing to the inlet end of the cylinder to close said one end of the housing, the opposite end of the housing being adapted to be connected to duct work,

5. A gasturbine comprising a turbine cylinder said casing to vexpose the rotor case when thev having an intermediate rotor case of circular and ends, said case being divided in an axial plane into two half sectionshaving flangeless joints ex tending lengthwise thereof, means detachably fastening the case sections together, an annular one-piece` end vbell disposed at each end of said case, means detachably connecting thejend bells casing having spaced end walls the inner one of s which surrounds said opposite end of the housing,

said casing` having an outlet, and means detachably connecting the housing to said surrounding casing wall, said housing being adapted to be moved axially into said casing to expose the `ro-l tor case when the housing is disconnected fromsaid cylinder and casing. v

6. A gas turbine'comprising a rotorcase open i at its opposite ends to form an inlet and an out- 1 let, a ring encircling said inlet and engaging the end of the case from which it projects iadiaIIy.

outwardly, means detachably connecting the case to said ring, a cylindrical housing having open` ends and encircling the case and spaced therefrom, means detachably connecting one end of the l housingto said ring to close said one end of the housing, an exhaust casing closing the opposite endof said housing and havingspaced end walls l the inner one of whichsurrounds said opposite end of the housing ywhereby the housing opens into the exhaust casing, means connected to the; case and supporting the casing, said casing hav-` ing an outlet, and means detachablyv connecting the housing to said surrounding casing wall,- said housing being adapted to be moved axially into housing is disconnected from said ring and caslng.

7. A gas turbine comprising a turbine cylinder provided at its opposite' ends with 'an' inlet and an outlet and having an intermediate rotor case, a housing having open ends and surrounding vsaid case and spaced therefrom, means detachably connecting one end of the-housing to the inlet.

end of the cylinder to close said one end of the housing, an exhaust casing closing the opposite end of said housing and fastened to the outlet end of the cylinder, said casing having spaced end walls the inner one of which surrounds said opposite end of the housing whereby the housing and said cylinder outlet open into the exhaust casing, said casing having an outlet opening, and means detachably connecting the housing to said surrounding casing wall, said housing being formed to slide axially into said casing to expose the rotor case when the housing is disconnected from said cylinder and casing.

8. A gas turbine comprising a turbine cylinder provided at its opposite ends with an inlet and an outlet and having an intermediate rotor case, a housing having open ends and surrounding said case kand spaced therefrom, means detachably connecting one end of the housing to the inlet end of the cylinder to close said one end of the housing, an exhaust casing closing the opposite end of said housing and fastened to the outlet end of the cylinder, said casing having spaced end walls the inner ones-of which surrounds said 4opposite end of the housing whereby the hpusing and said cylinder outlet open into the Aexhaust casing, said casing having an outlet opening,

means detachably connecting the housing to said surrounding casing wall, said housing being formed ofv telescoping annular sections, and

means detachably connecting said sections to" housing sections are telescoped.

9. A gas turbine comprising a turbine cylinder provided at its opposite .ends with anv inlet and an outlet and having an' intermediate rotor case, a housing having open ends and surrounding said case and spaced therefrom, means detachably connecting one end of the housing to the inlet end of the cylinder to close said one end of the housing, the opposite end of the housing being surrounded by a radial flange, an exhaust casing closing said opposite end of the housing and fastened to the outlet end of the cylinder, said casing having spaced end walls the inner one of which surrounds said flange whereby the housing and said cylinder outlet open into the exhaust casing, said casing having an outlet opening, a ring surrounding the housing and secured to said surrounding casing wall, and means detachably connecting said ring and ange together, said housing being formed to slide axially into said casing to expose the rotor case when the housing is disconnected from said cylinder and ring.

10. A gas turbine comprising a turbine cylinder provided at its opposite ends with an inlet and an outlet and having an intermediate rotor case, a housing having open ends and surrounding said case and spaced therefrom, means detachably connecting one end ofthe housing to the inlet end of the cylinder to close said one end of the housing, an exhaust casing closing the opposite end of said housing and fastened to the outlet end of the cylinder, said casing having spaced end walls the inner one of which surrounds said opposite end of the housing whereby the housing and cylinder case outlet open into the exhaust casing, said casing having an outlet opening, means detachably connecting the housing to said surrounding casing wall, said housing being formed of telescoping annular sections, the adjacent ends of said sections overlapping and being provided with overlapping radial anges, and means detachnected from said cylinder and casing and said ably clamping said flanges together, said housing being adapted to be telescoped into said casing to fully expose the rotor case when said housing sections are disconnected from each other and from said cylinder and casing.

11. A gas turbine comprising a turbine cylinder provided at its opposite ends with an inlet and an outlet and having an intermediate rotor case, a cylindrical housing having open ends and encircling said case and spaced therefrom, a ring encircling said inlet and connected to the end of the case from which it projects radially outwardly, said housing being formed of a pair of telescoping annular sections, the opposite ends of the inner section being encircledl by radial flanges, means detachably connecting one of said flanges to said ring, one end of the other section being provided with an inwardly extending radial flange overlapping the other flange on said inner section, means detachably connecting said overlapping flanges together, the end of said housing adjacent the cylinder outlet being encircled by a radial ange, an exhaust casing closing said lastmentioned end of the housing and fastened to the outlet end of the cylinder, said casing having spaced end walls the inner one of which encircles said last-mentioned flange whereby the housing and said cylinder outlet open into the exhaust casing, said casing havingan outlet opening, a ring encircling the housing, and means detachably connecting said last-mentioned ring to said encircling casing wall and adjacent housing flange, said housing being adapted to be telescoped into said casing to expose the rotor case when said section flanges are disconnected from each other and from said rings.

RONALD B. SMITH. FRITZ O. HENNIG.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,425,324 Kennedy Aug. 8, 1922 1,477,360 Junggren Dec. 11, 1923 1,985,964 Warren Jan, 1, 1935 2,169,092 Doran Aug. 8, 1939 2,256,221 Smith Sept. 16, 1941 2,288,734 Noack July 7, 1942 2,336,290 Phillips Dec. 7, 1943 

